#define _CRT_SECURE_NO_WARNINGS 1

class Solution
{
public:
    int triangleNumber(vector<int>& nums)
    {
        int count = 0, n = nums.size();
        sort(nums.begin(), nums.end());

        for (int i = n - 1; i >= 2; i--)
        {
            int left = 0, right = i - 1;
            while (left < right)
            {
                if (nums[left] + nums[right] > nums[i])
                {
                    count += (right - left);
                    right--;
                }
                else
                {
                    left++;
                }
            }
        }

        return count;
    }
};